The invention relates to a sorting method for sorting objects in a sorting installation in a plurality of sort runs. The invention also relates to sorting installations for sorting a plurality of objects in at least three sort runs, comprising: an inputting station for inputting the objects that are to be sorted into the sorting installation; an outputting station for outputting the objects that are to be sorted from the sorting installation; and a plurality of parking sections on which the objects are respectively parked until a given sort run has ended. Furthermore, the invention relates to a sorting system which combines a plurality of the aforesaid sorting installations with one another.
In general terms a sorting installation is designed to put quantities of articles that cover a large number of variations into a pre-defined sequence, using installation hardware designed to be as xe2x80x9cleanxe2x80x9d as possible. The sorting installation is customised to suit the user""s requirements in terms of its sorting output per hour and number of parts per sort run. The sorting output per hour is a variable that depends on the conveying speed of the conveying media and the necessary spacing of the items being conveyed, e.g. in order to interpose sets of points between them. The number of parts per sort run is a variable that is adapted to the user""s requirements and comprises, say, a delivery date or delivery run, one or more customers within this delivery, a required customer sequence, an article sequence specific to the customer such as sorting by article, colour, size or some other features, etc. The sorting installation may be integrated into existing types of organisers in order to carry out precisely this task. It is necessary to feed the articles for sorting into the system via an interpolation station and notify them to the installation""s control system via a reading station.
Corresponding sorting installations and associated sorting methods are for example known from the publication WO 95/27672. A schematised view of such a sorting installation is represented in FIG. 10. In the case of these sorting installations a plurality of parking sections S1, S2 and S3 are arranged one behind the other, along which the objects O1, O2, O3 can be parked behind the respective associated parking section stoppers St1, St2 and St3. Different groups of objects O are parked on each of the parking sections S. Preliminary sorting into group categories can take place when the objects O are input, whereas the subsequent sort runs put the objects O into the correct sequence within the groups. Relocators R1, R2 and R3 take the objects that are to be sorted from a transfer section to the respective parking sections S. In this way a very compact sorting installation can be accomplished with a large number of decision-making points, leading to the desired sorting result.
The only drawback of this is that where a plurality of sort runs are required, before each new sort run the objects parked one behind the other have to be brought back into the starting position onto the preliminary storage section V and there held up by the preliminary storage stopper StV ahead of the first relocator R1, so as to be able to begin a new sort run. To put this another way, the parking sections S have to be cleared, all the objects O placed in a queue one behind the other, and to perform the next sort run then separated once again, i.e. released one by one from the starting position, in order to be guided by relocators R from the transfer section back to the individual parking sections. This operation is repeated as often as necessary. The maximum number of objects for sorting depends on the number of parking sections and the number of sort runs. The possible, though not essential, preliminary sorting operation, i.e. division into groups in a buffer store, where each group may contain one or more sort run groups, does not count as a sort run. What is meant here by a sort run is a sorting step that contains a step resulting in the objects not only being allocated to individual groups but also being put into the correct sequence within these groups. Both the final division of the objects into the individual groups, i.e. parking sections, and the creation of the correct sequence within these groups can only be concluded once the last sorting step has been performed.
Furthermore, so-called cascade sorting installations are known from the prior art. One such sorting installation is schematised in FIG. 11. Sorting installations of this kind are distinguished by cascades of parking sections connected in series, which in the drawing are designated as S1A . . . S4A; S1B . . . S4B and S1C . . . S4C. The numbers 1 to 4 respectively designate the number of the parking section within a cascade, and the letters A, B, C the cascade. A sort run is characterised by the transfer of the objects from a first cascade A of parking sections S1A-S4A arranged parallel to one another to the next cascade B, and so on as far as the last cascade, here C, the objects divided in sequence by groups between the various parking sections and sorted into sequence being taken thereto and removed therefrom. Filling the first block starting from a preliminary sorting section or by direct input also counts as a sort run (1st sort run). Therefore a number of cascades of parking sections that corresponds to the number of sort runs must be provided. The advantage with these cascade-type sorting installations is that they eliminate the need for a time-delay by returning the objects to the starting position before each new sort run, and the sort run takes place by direct transfer from one cascade to the next and so on. This prior art does, however, have the drawback that the space taken up by these sorting installations (constructional volume) is very great, for as many cascades must be provided as sort runs are necessary. Thus the costs of building and running them are also high, for each cascade essentially necessitates the full building cost of an entire sorting installation, with parking sections, parking controller, and segregator. Moreover, such cascade-type sorting installations are relatively inflexible because, as mentioned, the maximum number of sort runs is predetermined from an engineering aspect by the number of cascades, and the number of sections per cascade reflects the possible sorting criteria per sort run. A disadvantage also stems from the fact that the objects to be sorted must be supplied to the system in an orderly manner and already in groups.
DE 690 26 794 T2 discloses a sorting installation having a main conveying line, a main unloading line and a plurality of parking sections which are connected to the main conveying line and the main unloading line and on which the objects that are for sorting are respectively parked until a given sort run has finished.
From DE 197 09 232 A1 a sorting installation is known which involves sorting the objects that are for sorting in a plurality of sorting compartments in such a manner that a plurality of sort runs are performed one after the other in accordance with a fixed sequence.
It is the underlying object of the invention to develop the sorting method of the type mentioned in the introduction in such a way that even with a small constructional volume and modest building costs a fast sorting operation nevertheless becomes possible, and to create a corresponding sorting installation and a corresponding sorting system.
In accordance with the invention this is achieved by a sorting method for sorting objects in a sorting installation with at least the following sorting steps:
a) first sort run, in which objects are put onto parking sections of a first block of parking sections;
b) second sort run, in which objects are transferred from the first block of parking sections into a second block of parking sections; and
c) third sort run, in which objects are transferred from the second block of parking sections back to the first block of parking sections.
Under a first alternative embodiment of a sorting installation operating by the sorting method according to the invention, the refinement in accordance with the invention is characterised by:
division of the parking sections into a first and second block of parking sections;
a first transfer section which connects the inputting station to the first block of parking sections in such a manner that the latter can be filled from the inputting station in a first sorting step;
a second transfer section which connects the first block to the second block in such a manner that the objects are transferred from the first block to the second block in a second sort run; and
a third transfer section which connects the second block to the first block in such a manner that the objects are transferred from the second block back to the first block in a third sort run.
Under a second alternative embodiment of a sorting installation operating by the sorting method according to the invention, the refinement in accordance with the invention is characterised by:
division of the parking sections into a first and second block of parking sections;
a connection which joins the inputting station to the first block of parking sections in such a manner that the latter can be filled from the inputting station in a first sorting step;
a first set of relocators which connects the first block to the second block in such a manner that the objects are transferred from the first block to the second block in a second sort run; and
a second set of relocators which connects the second block to the first block in such a manner that the objects are transferred from the second block back to the first block in a third sort run.
More than two sorting blocks may also be provided in the sorting installation if it is desired to enhance the sorting output per unit of time. In the case of more than two sorting blocks, the sorting method in accordance with the invention with the three minimum steps can also be carried out within a more complex sorting operation comprising more than three sorting steps, or take place at the start or the end of the more complex sorting operation. Any desired number of sorting steps can be chosen, which means that the FIGURE of two sorting blocks and three sorting steps is merely to be regarded as the minimum number.
The sorting method in accordance with the invention, and the two alternative sorting installations for carrying out this sorting method combine together three very essential advantages, as already intimated in the statement of the problem:
The first essential advantage is explained by the fact that the interplay between the blocks of parking sections can be repeated as often as desired and thus from the engineering aspect no limits are set in terms of the number of objects to be sorted, apart from the fact that there must be room for these objects in the sorting installation. This is in contrast to the cascade-type conveyor under the prior art, where the number of sort runs is predetermined from the engineering aspect by the number of cascades, and hence the maximum number of objects to be sorted is predetermined from the engineering aspect by the number of cascades and the number of parking sections within the cascades, each of the cascades standing for a sorting step.
As the second essential advantage the sorting installation in accordance with the invention ensures a small constructional volume, since irrespective of the number of objects to be sorted only two blocks of parking sections are needed as a minimum solution. By contrast, in the case of the cascade-type sorting installation more than two cascades may be needed in certain circumstances in order to achieve a depth of sort that extends to the individual part. This increases not only the constructional volume, but also the building and running costs, on account of the many parking sections, stoppers and controls therefor.
The third essential advantage offered by the sorting installation in accordance with the invention is a fast sort process, because for each additional sort run after the first sort run the transfer takes place direct from one block of parking sections to the second and from there back to the first, etc., and thus there is no necessity for clearing the parking sections, parking on a preliminary storage section, and separating the articles again in order to perform the next sort run, as is necessary under the prior art represented in FIG. 10.
Thus, for the first time, in terms of high sort rate the sorting installation in accordance with the invention makes it possible to enjoy the advantages of a cascade-type sorting installation as depicted in FIG. 11, but in terms of flexibility and small constructional volume makes it possible to enjoy and even top the advantages of a sorting installation as depicted in FIG. 10. Apart from this, the sorting installation in accordance with the invention can additionally be combined with a cascade-type conveyor, or else the sorting method in accordance with the invention can be added on to a sorting method for a cascade-type conveyor, or vice versa.
Corresponding advantages are provided by the sorting method in accordance with the invention, which by transferring from one block to the next and vice versa ensures a sorting process that is both fast and flexible by virtue of the fact that it permits any desired number of sorting steps for any desired sort criteria.
The range of objects for sorting is unlimited, provided the objects satisfy the criterion of being able to be individually separated. To name just one example, the objects may be clothes hangers with various items of clothing on them. These can be conveyed directly, or else in a particularly practical manner be suspended from rolling fixtures which are conveyed along a track system.
Practical refinements of the first alternative embodiment of the sorting installation in accordance with claims 8 to 17 will now be discussed:
One practical refinement is distinguished by the fact that the second and third transfer sections run in opposite directions and the parking sections extend between these transfer sections and are connected to them, with the result that the parking sections at the same time serve as relocators, which by parking and re-releasing the objects for the following sort run relocate these objects from the second transfer section to the third transfer section running in the opposite direction, or vice versa.
Advantageously the parking sections are arranged parallel to one another and within a respective block are identical in length. Advantageously all the parking sections may even run parallel to one another irrespective of which block they belong to. It is, however, also conceivable for the parking sections not to run parallel to one another within a block, but to run at an angle to one another, or even to be arranged one behind the other in a single section, or they may be offset relative to one another and their parking sections may be arranged at an angle to one another from one block to the next. The advantage of the parallel arrangement is that it means a particularly compact layout.
In accordance with one practical refinement the first transfer section runs in the shape of a C around the first block. A return section behind the second block may advantageously also open out into the first transfer section. In the case of this arrangement both blocks can be, so to speak, more or less framed by the first transfer section and return section, which makes it possible to accommodate the blocks and the transfer section and return section which surrounds them externally in a space-saving manner. Advantageously the second transfer section is arranged parallel to a portion of the first transfer section.
In accordance with a practical refinement of the invention a preliminary sorting section is connected upstream of the first block of parking sections. This makes it possible for the operator to firstly load all the objects onto the preliminary sorting section and park them there, and then to release them one by one and thus initiate the first sorting step by systematic filling of the first block; the individual parking sections of the first block each become filled with associated objects. The preliminary sorting section is not strictly necessary, since the objects may be loaded straight onto the parking sections of the first block, but offers the system the possibility of a required/actual object comparison of the loaded objects before initiating the first sort run.
The preliminary sorting section should advantageously be at least equal in length to the sum of the lengths of the parking sections of the first block.
As already explained above, in order to achieve an even higher sort rate it may be useful to provide not just two blocks of parking sections, but three or more blocks of parking sections; the interplay can then also take place simultaneously between a plurality of blocks in each case. Paradoxically, with a higher number of blocks it is even possible to reduce the hardware employed by reducing the parking sections and thus the numbers of points. A more detailed explanation is to be found in the exemplifying embodiments depicted in FIGS. 6 and 7.
A greater number of objects capable of being loaded onto the sorting installation in the inputting step can be achieved in a straightforward manner by interposing a buffer store in the first transfer section, which store in turn features a plurality of buffer store parking sections. For example, the buffer store may consist of a number of parking sections running parallel to one another, and for each sorting operation (which includes a plurality of sort runs) the quantity of objects to be sorted per sorting operation can be loaded onto one of the parallel buffer store parking sections, or else a plurality of groups for one respective sorting operation may even be arranged on the individual buffer store parking sections.
Even greater flexibility is obtained by configuring the buffer store in accordance with a practical refinement in such a way that one or more parking sections are each a constituent part of a closed circuit which is connected to the first transfer section. In this way objects from the buffer store can systematically be loaded onto the transfer section, that is to say for example systematically an individual object or a group of objects loaded from a given buffer store parking section onto the transfer section at the desired point in time, although these buffer store parking sections (or rather buffer store circuits) may be filled in a random fashion.
The second alternative embodiment of the sorting installation as claimed in claims 18 to 24 will now be discussed, detailing only those features of said alternative embodiment which have not already been explained above in relation to the first alternative embodiment and which apply correspondingly in respect of the second alternative embodiment:
According to one practical refinement the first and second block of parking sections incorporate parking sections connected one behind the other in series, with the parking sections of the first block being adapted to be filled in the opposite direction to the parking sections of the second block, and vice versa.
In an advantageous manner at least one of the relocators forms part of a parking section or a complete parking section. Advantageously at least one of the parking sections of the first block runs parallel to at least one of the parking sections of the second block. It is even possible for all the parking sections of the first block to run parallel to all the parking sections of the second block. To put this in simple terms, the objects can be parked on parking sections of any desired form, i.e. straight sections or curved sections, or the relocators, which in a straightforward scenario constitute a length of track which is preferably curved and is joined to the straight length of track by means of points. The relocators may also be configured as a transfer wheel. In an extreme scenario the relocators are configured to be elongate, predominately straight and parallel to one another, and act as the only parking sections, thereby resulting in the above first alternative embodiment of the sorting installation in accordance with the invention.
As with the first alternative, advantageously a preliminary storage section may be disposed upstream of the first block of parking sections, the length of the preliminary storage section advantageously being at least identical to the sum of the lengths of the parking sections of the first block.
If a plurality of sorting installations are disposed in series one behind the other or connected in parallel by means of a transfer section connecting same, this then results in a practical sorting system.
There now follows a discussion of the sorting method in accordance with the invention as claimed in claims 1 to 7:
In an especially practical manner in terms of the desired high ratio of the number of objects sorted in a sorting operation to the constructional volume, and the sorting rate due to short paths, i.e. avoiding unnecessary routing, the sorting method in accordance with the invention is refined in such a way that the parking sections of the first block are uniformly filled in the first sort run, and in the subsequent sort runs the uniform filling of the parking sections of the first and second block is retained irrespective of the number of sort runs. The positive result thereby achieved is that even after the last sort run has been completed, all the parking sections of the particular block on which the objects that have been sorted into groups and into sequence within the groups are situated can be filled completely. This on the one hand prevents the parking sections from being unnecessarily long, which would otherwise be caused by some parking sections being filled with many objects, while others are almost or half empty, and on the other hand it means that no long routes have to be taken along unnecessarily long parking sections during the sorting process, and this measure also results in the smallest possible constructional volume.
The number of objects to be sorted as a maximum is calculated by taking the number of parking sections of a block as the base, to the power of the number of sort runs as the exponent.
In an advantageous manner exactly three, or more than three, sort runs may be carried out. As has already been explained, it is particularly advantageous to always observe uniform filling of all the parking sections of a respective completely filled block via all the sorting steps, irrespective of the number of sort runs.
If all the objects that are to be sorted are parked on a preliminary storage section ahead of the first block, this offers the advantage of already accomplishing the first sort run along with the filling of the first block of parking sections, and in the inputting step possibly loading the objects already pre-sorted onto the preliminary storage section. Irrespective of the operation of the sorting installation, the inputting of the objects onto the preliminary storage section can be done manually. If it is desired to input a larger number of objects in the inputting step than can be dealt with by the sorting machine in a sorting operation, it is advisable to input them into a buffer store.
A further enhancement of output and flexibility in sorting is achieved by the fact that a plurality of sorting installations as claimed in claims 8 to 24 are connected in series behind one another or in parallel with one another by means of a transfer section (26) which connects them together. This creates a sorting system in which a large number of sorting operations can take place in parallel.